Can farmers earn carbon credits by cutting back on nitrogen fertiliser?

Low-till farming keeps carbon locked in soil, but the amounts rarely justify the cost of trying to earn carbon offsets. A new report from The Climate Trust, however, identifies overuse of nitrogen fertiliser as an under-recognised climate contributor, and sees carbon finance as a way of reducing it.

Of all the sticky subjects wrapped up in global warming and international talks about curbing climate change, perhaps agriculture is one of the stickiest. After all, agriculture is a hefty contributor to global greenhouse-gas emissions, but it’s also what feeds us all.

The US Environmental Protection Agency (EPA) estimates global emissions released through cropland soil management, livestock, biomass burning and rice production at 14 per cent. And a Food and Agriculture Organization report found emissions from agriculture surpassed those from deforestation over the last decade. Plus, deforestation often occurs to clear land in order to grow crops.

Moreover, the growing world population requires a sustainable agricultural system but inclement weather associated with climate change, made worse by high emission rates, threatens food production.

Over the past few years, climate negotiators have begun to notice the importance of agriculture, as Steve Schwartzman of the Environmental Defense Fund noted earlier this year. And the United Nations even went so far as to name 2015 the International Year of Soils, highlighting sustainable management practices like crop diversification.

Scientists have long known that practices like low-till farming keep carbon locked in the soil, but the law of diminishing returns had made it difficult to attract carbon finance to such projects – except for when they noticeably increase yields, as farmers in some parts of Kenya and elsewhere have found.

A workable solution?

Last month, US-based nonprofit The Climate Trust released research on using emissions reduction in agriculture operations as offsets in the carbon markets. The Trust’s research looks specifically at improved use of nitrogen fertiliser, which releases nitrous oxide, a greenhouse gas 280 times more potent than carbon dioxide.

The EPA ranks this nutrient pollution  as one of the US’s most costly and widespread environmental challenges, because it acts as a greenhouse gas in the air, and excess nitrogen leeches into waterways, leading to algae blooms that suck up oxygen and kill fish.

The Climate Trust says carbon markets hold potential to incentivize responsible land-use practices, encouraging nutrient stewardship. The Trust’s report found that transitioning fertilizer use to best management practices could generate up to 2.7 million offsets-the equivalent of taking 162,000-568,000 cars off the road each year. And that’s a conservative estimate, report authors say.

“By creating innovative incentives that encourage farmers to adopt responsible nutrient management practices, we can make a big environmental impact,” said Lara Moody, the Senior Director of stewardship and sustainability for The Fertilizer Institute (TFI), a nonprofit involved in this research.

Encouraging environmentally friendly fertiliser use

This report is The Climate Trust’s latest research stemming from TFI-led efforts to entice US corn and soybean growers into adopting best management practices when applying nitrogen fertilisers. In 2011, the US Department of Agriculture awarded them, along with other organizations, with a Conservation Innovation Grant to develop and test responsible methods.

“Utilising best management practices provides a wealth of benefits including water quality protection and an improved bottom line for farms,” Moody said in a statement.

Although the report cites potential, it also lists significant obstacles before significant carbon credit generation from nutrient management.

Essentially, the report authors say, this report is the early workings of a roadmap to develop large-scale nutrient stewardship and carbon crediting from agriculture.

The Trust’s research explores nutrient management credits through corn or corn-soybean rotation operations in the corn-heavy Midwest and Great Plains states because that’s what the current credit calculation protocols are best suited for.

The best management practices focus on the adoption of what’s called 4R Nutrient Stewardship, a science-based approach to applying nitrogen fertilizer for optimal use in terms of high and healthy yields but without the environmental harm.

It consists of four parts:

  • Right source: The type of fertilizer applied can impact the amount of nitrogen that leaves the field. For example, ammonium (NH4 + ) fertilisers are more stable than some other forms and can minimise leaching.
  • Right rate: Using field measurements of nitrogen in soils and knowledge of the crop’s needs, farmers can better estimate the amount of fertilizer to apply.
  • Right time: Timing the application to coincide with when the crop needs the nutrient most can help reduce losses.
  • Right place: Applying nutrients closer to where the crops will be able to make the best use of them can also help to reduce nutrient loss.

Farmers practicing this type of fertiliser management have an opportunity to avoid emissions, generate credits and earn revenue through the carbon markets.

But the dynamics of soils are immensely complex making it hard for farmers and nutrient management project developers to capture the full potential of 4R Stewardship, the report says.

It’s one of many challenges such a system faces. Measuring agricultural nutrients is difficult from both a practical and political position, report authors say. Not all soils are eligible, for instance, and there are varying degrees of participation from farmers, not to mention the rigors of carbon markets, having to prove additional emissions reductions. And, of course, there is a severe lack of data surrounding nutrient management.

Report authors note this last point as one of the biggest barriers to a crediting system, which requires a comprehensive data collection. The Trust also highlights unproven protocols as another big challenge. The fact that a clear buyer of these credits hasn’t yet emerged, is also a large problem.

Encouraging behaviour change

Nevertheless and despite these many mitigating factors, The Climate Trust determines 10-15 per cent of acres planted for corn could generate the aforementioned 2.7 million offsets. The number is ambitious for a nascent offset market, the report says.

The report also sees potential, though difficult, for other crops to eventually generate credits using protocols moderated for various crops and regions.

The risks are daunting and serious which is why authors suggest developing carbon crediting from agriculture carries a longer-term developing stage, 5-10 years long.

But addressing emissions in agriculture is imperative and a vital part of slowing the acceleration of climate change. Utilising the carbon markets allow farmers to capitalize on the economic benefits of their improved land practices, Elizabeth Hardee, a Senior Analyst and lead report author at The Climate Trust, said in a statement.

There is huge potential for nutrient management credits in the US, she says, “And with the right roadmap, agriculture itself may become a change agent capable of reducing global emissions.”

This story was published with permission from Ecosystem Marketplace

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